Easy Thermo Sudoku

New to Thermo Sudoku? Easy puzzles are designed to teach the core constraint with minimal complexity. Each puzzle uses simpler configurations so you can focus on understanding the rule before anything else.

▶ Play Easy Thermo Sudoku All Thermo Sudoku Difficulties

What to expect at Easy level

Easy Thermo Sudoku puzzles are calibrated so the variant constraint alone is often enough to reveal cells directly. You'll rarely need to look beyond a single unit at a time. Mistakes are easy to catch because the constraint violations are obvious.

Recommended for players who have never tried Thermo Sudoku before, or those who prefer a relaxed, confidence-building experience.

Difficulty overview

LevelCluesTechniques neededAvg. time
Easy ManyBasic elimination5–10 min
Medium ModerateSingles, pairs10–20 min
Hard FewAdvanced logic20–40 min
Expert MinimalFull mastery40+ min

About Thermo Sudoku

Difficulty
★★★★☆
4/5
Constraint Type
Line Constraints
Typical Givens
20–28
Avg. Solve (Easy)
10 min

Thermo Sudoku overlays thermometer shapes on the grid. Each thermometer has a bulb (circle) at one end and a tip at the other. The digits along any thermometer must strictly increase from the bulb to the tip. Combined with standard Sudoku constraints, this creates powerful chains of deductions — knowing the bulb is at least 1 and the tip is at most 9, you can calculate the range of valid values for each cell on the thermometer based on its position.

Solving Techniques for Easy Level

Technique Description Level
Range Restriction from Length A thermometer with N cells must use N strictly increasing distinct values. The bulb is at least 1 and the tip is at most 9, giving a calculable valid range for each cell. Beginner
Minimum/Maximum Bounding The bulb value is ≤ 9 − (N − 1). The tip value is ≥ N. Apply these bounds immediately to prune all thermometer candidates. Beginner

Ready to go deeper? Try Medium Killer Sudoku to unlock Intermediate techniques.

Average Solve Time by Difficulty

Easy
10 min
Medium
22 min
Hard
45 min
Expert
75 min

Frequently Asked Questions

Which end is the bulb?
The circle (round end) is the bulb — digits increase from the bulb towards the tip.
Can a thermometer cross box boundaries?
Yes — thermometers can cross any boundary.
Must digits be strictly increasing?
Yes — strictly increasing means no two adjacent thermometer cells may share the same digit.